超临界状态下纳米金刚石复合电铸技术研究

发布时间：2018-06-20 04:42

本文选题：超临界CO_2流体 + 纳米金刚石　；参考：《江苏理工学院》2015年硕士论文

【摘要】：超临界流体复合电铸技术是基于电沉积原理,集金属复合材料制备与成形为一体的精密成形制造技术,近年来新发展起来的制备高性能结构件行之有效的方法。本文围绕超临界二氧化碳流体纳米复合电铸技术,对其工艺过程开展数值模拟、试验研究与分析。(1)构造三维电铸体系模型,利用Comsol Multiphysics有限元分析软件,耦合分析了电场分布、流场分布、电铸层厚度分布情况和阴极表面镍离子浓度变化规律。研究表明对于平板型电铸,在中部区域,电场分布较为均匀,与外加电流密度相符,在边缘处,由于形状变化,电流密度呈激增趋势。对于微细电铸,电场线在微结构入口处弯曲程度和稠密度逐渐加大,微结构中间部分电场线较少,微结构边缘处电场线稠密,且进入微结构以后电场线变得方向一致,微结构内部的电场分布稳定均匀有次序。电铸层生长情况仿真值与电流密度分布相符合,阴极表面镍离子浓度呈先减少后增大的趋势。(2)提出了超临界纳米金刚石复合电铸工艺优化方法,获得了影响电铸层性能的工艺规律,利用自主研发的超临界电沉积装置,开展其工艺试验研究。通过正交试验,得出影响电铸层显微硬度的各工艺参数顺序与最佳值分别为(从大到小):电流密度(9A/dm2)、金刚石添加量(60g/L)超临界压力(14MPa)超临界温度(40℃)。通过单因素试验,分析研究了各工艺参数对电铸层显微硬度和表面微观形貌的影响规律。研究发现,SCF-CO2条件下,由于其良好的传质扩散性、混溶性和润湿特性,制备的Ni-diamond复合电铸层显微硬度可达954HV(200g),比普通条件下提高80%,且复合粒子均匀性显著提高,说明采用超临界环境对制备的Ni-diamond复合电铸层的更具力学性能优势;从XRD图谱中发现,和普通环境下相比,超临界环境下镍结晶面择优取向强弱有所变化,其中晶面(111)上的衍射峰被抑制,晶面(200)上的衍射峰得到加强。(3)开展SCF-CO2复合电铸应用基础研究,成功制备微细复合电铸件。在平板电铸的工艺参数基础上,针对“十字”型微细结构,开展复合电铸工艺研究,分析了各工艺参数对其表面形貌影响规律,并为下一步工程化应用打下了良好的基础。
[Abstract]:The technology of supercritical fluid composite electroforming is based on the principle of electrodeposition and the precision forming technology of the preparation and forming of metal composite. In recent years, a new method for preparing high performance structural parts has been developed. This paper focuses on the technological process of the supercritical carbon dioxide fluid nanocomposite electroforming technology. Simulation, experimental research and analysis. (1) constructing a three-dimensional electroforming system model, using Comsol Multiphysics finite element analysis software, coupled analysis of the distribution of electric field, the distribution of flow field, the thickness distribution of the electroforming layer and the change law of the concentration of nickel ions on the cathode surface. The research shows that the distribution of electric field is more uniform in the middle region of the plate type electroforming, and the distribution of the electric field is more uniform in the middle region. The current density is consistent with the current density, and the current density increases sharply at the edge. For micro electroforming, the degree and density of the electric field line at the entrance of the micro structure are gradually increased, the electric field line in the middle part of the micro structure is less, the electric field line is dense at the edge of the micro structure, and the electric field line becomes the same in the direction of micro structure, and the direction of the electric field becomes uniform after the micro structure. The distribution of electric field in the structure is stable and uniform. The simulation value of the growth of the electroforming layer conforms to the distribution of current density, and the concentration of nickel ions on the cathode surface decreases first and then increases. (2) the optimization method of the supercritical nano diamond composite electroforming process is put forward, and the process law of the performance of the electroforming layer is obtained, and the independent research and development of the electroforming layer is obtained. Through orthogonal test, the sequence and optimum value of the technological parameters affecting the microhardness of the electroforming layer are (from large to small): current density (9A/dm2) and the supercritical pressure (60g/L) supercritical pressure (14MPa) at supercritical temperature (40). Through a single factor test, the analysis and study of each of the various parameters of the microhardness of the electroforming layer are obtained. The effect of process parameters on the microhardness and surface micromorphology of the electroforming layer was investigated. The results showed that under SCF-CO2 conditions, the microhardness of the prepared Ni-diamond composite electroforming layer was up to 954HV (200g) due to its good mass transfer diffusibility, miscibility and wetting properties, which was 80% higher than that under the ordinary condition, and the uniformity of the composite particles was greatly improved. The Ni-diamond composite electroforming layer has a more mechanical advantage over the supercritical environment. It is found from the XRD map that the preferred orientation strength of the nickel crystal surface changes in the supercritical environment, in which the diffraction peak on the crystal surface (111) is suppressed and the diffraction peak on the crystal surface (200) is strengthened. (3) the SCF-CO2 recombination is carried out. Based on the technological parameters of the plate electroforming, based on the technological parameters of the flat plate electroforming, the study of the composite electroforming process is carried out on the basis of the "cross" micro structure. The influence of the process parameters on the surface morphology is analyzed, and a good foundation is laid for the next engineering application.
【学位授予单位】：江苏理工学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ153.4

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